1. Field of the Invention
The present invention relates to a rotary electric machine with a stator elastic support structure, which effectively reduces noise while preventing a heat deterioration of an elastic member in low cost. The present invention is suitably applied to a vehicle AC generator.
2. Description of the Related Art
In a rotary electric machine described in JP-B2-5-50217, an elastic member is inserted between a stator core and a frame for reducing a magnetic noise. The elastic member has a structure where a rubber material is inserted between an outer metal cylinder and an inner metal cylinder.
In a rotary electric machine described in U.S. Pat. No. 5,629,575, a shock absorbing member is inserted between a stator core and a frame so that an arrangement position of the stator core can be readily set.
Further, a rotary electric machine described in JP-B2-2927288, each of U-shaped conductor segments is inserted into a pair of slots, and top parts of each conductor segment is connected to form a stator winding.
In recent years, it is requested to reduce a magnetic noise generated in a rotary electric machine. If the rotary electric machine is entirely covered by a noise insulation case, the magnetic noise can be reduced. However, in this case, it is difficult to radiate heat generated by a stator winding and a stator core, through a frame. Accordingly, temperature of the stator winding is increased, and an elastic member or an insulation film is readily heat-deteriorated. To overcome this problem, when the elastic member is formed of a heat-resistance rubber such as a silicon rubber and a fluoro rubber, elastic performance of the elastic member is decreased. Therefore, the elastic member does not effectively absorb a vibration transmission and the magnetic noise. Further, due to high cost of the heat-resistance rubber, it is difficult to use the heat-resistance rubber as the elastic member actually. On the other hand, when a thickness of the elastic member is increased for absorbing the vibration transmission from the stator core to the frame, it is difficult to transmit heat generated by the stator winding to the frame, and heat deterioration of the elastic member or the insulator film is facilitated.
Further, when the dimension of the stator winding or the stator core is increased for reducing heat generated from the stator winding or the stator core, the size and the wight of the rotary electric machine are increased, and the machine is impossible to be actually used.
In view of the foregoing problems, it is an object of the present invention to provide a rotary electric machine with a stator elastic support structure, which reduces noise while preventing heat deterioration of an elastic member or an insulator film, in low cost.
According to the present invention, in a rotary electric machine, a stator core having a plurality of slots is disposed to be supported in a frame, a stator winding includes a plurality of conductor segments each of which is formed into an approximate U-shape having a pair of leg parts, and an elastic member is disposed between the stator core and the frame to be inserted therebetween. The conductor segments are inserted into the slots of the stator core in such a manner that, the leg parts of each conductor segment penetrate through the slots from one end of the stator core to the other end thereof, and are connected at top ends. Further, the conductor segments are arranged to have a predetermined clearance between adjacent two thereof at both coil ends of the stator winding, into which air blown by a cooling fan flows. Accordingly, the clearances between the conductor segments define an air passage through which air blown by the cooling fan flows, and the stator winding can be effectively cooled. Because each the conductor segment has a large sectional area in a radial direction, heat generated by the stator core can be readily transmitted to the both coil ends of the stator winding. Therefore, the temperature of the stator winding can be effectively reduced without increasing dimensions of the stator core and the stator winding. Thus, when the elastic member is inserted between the frame and the stator core for reducing a magnetic noise, or when the conductor segments are covered by an insulation film, it can effectively prevent a heat deterioration of the elastic member or the insulation film, due to heat radiated from the stator winding and the stator core, in low cost.
Preferably, the elastic member has a cylindrical elastic portion made of rubber, a first cylindrical metal portion integrated with an inner surface of the cylindrical elastic portion, and a second cylindrical metal portion integrated with an outer surface of the cylindrical elastic portion. Therefore, it is possible to strongly bonding the elastic member and the frame or the stator core, by using the elastic performance of the elastic portion and the strength of the first and second cylindrical metal portions.
Further, the frame includes first and second frame parts separated in an axial direction of the rotor, the first and second frame parts are disposed to be fastened in the axial direction while press-contacting outer peripheral edge parts of the stator core through the elastic member. Therefore, the elastic member can be readily inserted between the stator core and the first and second frame parts. In this case, the first and second frame parts are fastened through a fastening member such as a through bolt, and a reduction effect of the magnetic noise due to the elastic member and a reduction effect of vibration of the stator core can be arbitrarily adjusted.
Preferably, the elastic member includes first and second ring-like elastic parts each of which has an approximate L-shaped cross-section in the axial direction. Therefore, the stator core can be accurately supported in the first and second frame parts through the ring-like elastic parts.
More preferably, a middle part of an outer peripheral surface of the stator core in the axial direction is disposed to expose to an outside. Therefore, the exposed part of the outer peripheral surface of the stator core can be effectively cooled by an air flow, for example.
On the other hand, an inner peripheral surface of the frame has plural frame slots extending in the axial direction of the rotor at positions opposite to the stator core, and the elastic member includes plural elastic parts which are inserted into the frame slots to have elastic surfaces corresponding to the inner peripheral surface of the frame. Therefore, when an electrical power is generated, the elastic member is heat-expanded to protrude to a radial inner side and to elastically support the outer peripheral surface of the stator core.
Preferably, the frame is disposed to define a liquid fluid passage through which a cooling fluid for cooling the stator core flows, and the elastic member is disposed between the frame and the stator core to directly contact the cooling fluid. Therefore, the magnetic noise can be reduced while the heat deterioration of the elastic member can be further effectively prevented.